(a) Prohibition in general 
No damages, interest on damages, costs or attorneys fees may be recovered under section 4, 4A, or 4C of the Clayton Act (15 U.S.C. 15, 15a, or 15c) in any claim against a person based on any official action directed by a local government, or official or employee thereof acting in an official capacity.

(b) Nonapplication of prohibition for cases commenced before effective date of provisions 
Subsection (a) of this section shall not apply with respect to cases commenced before the effective date of this Act.